Gene Expression Correlation Analysis Reveals MYC-NAC Regulatory Network in Cotton Pigment Gland Development

Plant NAC (NAM, ATAF1/2, and CUC2) family is involved in various development processes including Programmed Cell Death (PCD) associated development. However, the relationship between NAC family and PCD-associated cotton pigment gland development is largely unknown. In this study, we identified 150, 153 and 299 NAC genes in newly updated genome sequences of G. arboreum, G. raimondii and G. hirsutum, respectively. All NAC genes were divided into 8 groups by the phylogenetic analysis and most of them were conserved during cotton evolution. Using the vital regulator of gland formation GhMYC2-like as bait, expression correlation analysis screened out 6 NAC genes which were low-expressed in glandless cotton and high-expressed in glanded cotton. These 6 NAC genes acted downstream of GhMYC2-like and were induced by MeJA. Silencing CGF1(Cotton Gland Formation1), another MYC-coding gene, caused almost glandless phenotype and down-regulated expression of GhMYC2-like and the 6 NAC genes, indicating a MYC-NAC regulatory network in gland development. In addition, predicted regulatory mechanism showed that the 6 NAC genes were possibly regulated by light, various phytohormones and transcription factors as well as miRNAs. The interaction network and DNA binding sites of the 6 NAC transcription factors were also predicted. These results laid the foundation for further study of gland-related genes and gland development regulatory network.

Molecular cloning and characterization of GhERF105, a gene contributing to the regulation of gland formation in upland cotton (Gossypium hirsutum L.)

Background Gossypium hirsutum L. (cotton) is one of the most economically important crops in the world due to its significant source of fiber, feed, foodstuff, oil and biofuel products. However, the utilization of cottonseed was limited due to the presence of small and darkly pigmented glands that contain large amounts of gossypol, which is toxic to human beings and non-ruminant animals. To date, some progress has been made in the pigment gland formation, but the underlying molecular mechanism of its formation was still unclear. Results In this study, we identified an AP2/ERF transcription factor named GhERF105 (GH_A12G2166), which was involved in the regulation of gland pigmentation by the comparative transcriptome analysis of the leaf of glanded and glandless plants. It encoded an ERF protein containing a converved AP2 domain which was localized in the nucleus with transcriptional activity, and showed the high expression in glanded cotton accessions that contained much gossypol. Virus-induced gene silencing (VIGS) against GhERF105 caused the dramatic reduction in the number of glands and significantly lowered levels of gossypol in cotton leaves. GhERF105 showed the patterns of spatiotemporal and inducible expression in the glanded plants. Conclusions These results suggest that GhERF105 contributes to the pigment gland formation and gossypol biosynthesis in partial organs of glanded plant. It also provides a potential molecular basis to generate ‘glandless-seed’ and ‘glanded-plant’ cotton cultivar.

Molecular cloning and characterization of GhERF105, a gene contributing to the regulation of gland formation in upland cotton (Gossypium hirsutum L.)

Background: Gossypium hirsutum L. ( cotton) is one of the most economically important crops in the world due to its significant source of fiber, feed, foodstuff, oil and biofuel products. However, the utilization of cottonseed was limited due to the presence of small and darkly pigmented glands that contain large amounts of gossypol, which is toxic to human beings and non-ruminant animals. To date, some progress has been made in the pigment gland formation, but the underlying molecular mechanism of its formation was still unclear.Results: In this study, we identified an AP2/ERF transcription factor named GhERF105 (GH_A12G2166), which was involved in the regulation of gland pigmentation by the comparative transcriptome analysis of the leaf of glanded and glandless plants. It encoded an ERF protein containing a converved AP2 domain which was localized in the nucleus with transcriptional activity, and showed the high expression in glanded cotton accessions that contained much gossypol. Virus-induced gene silencing(VIGS) against GhERF105 caused the dramatic reduction in the number of glands and significantly lowered levels of gossypol in cotton leaves. GhERF105 showed the patterns of spatiotemporal and inducible expression in the glanded plants. Conclusions: These results suggest that GhERF105 contributes to the pigment gland formation and gossypol biosynthesis in partial organs of glanded plant. It also provides a potential molecular basis to generate ‘glandless-seed’ and ‘glanded-plant’ cotton cultivar.

Molecular cloning and characterization of GhERF105, a gene contributing to the regulation of gland formation in upland cotton (Gossypium hirsutum L.)

Background: Gossypium hirsutum L. ( cotton) is one of the most economically important crops in the world due to its significant source of fiber, feed, foodstuff, oil and biofuel products. However, the utilization of cottonseed was limited due to the presence of small and darkly pigmented glands that contain large amounts of gossypol, which is toxic to human beings and non-ruminant animals. To date, some progress has been made in the pigment gland formation, but the underlying molecular mechanism of its formation was still unclear.Results: In this study, we identified an AP2/ERF transcription factor named GhERF105 (GH_A12G2166), which was involved in the regulation of gland pigmentation by the comparative transcriptome analysis of the leaf of glanded and glandless plants. It encoded an ERF protein containing a converved AP2 domain which was localized in the nucleus with transcriptional activity, and showed the high expression in glanded cotton accessions that contained much gossypol. Virus-induced gene silencing(VIGS) against GhERF105 caused the dramatic reduction in the number of glands and significantly lowered levels of gossypol in cotton leaves. GhERF105 showed the patterns of spatiotemporal and inducible expression in the glanded plants. Conclusions: These results suggest that GhERF105 contributes to the pigment gland formation and gossypol biosynthesis in partial organs of glanded plant. It also provides a potential molecular basis to generate ‘glandless-seed’ and ‘glanded-plant’ cotton cultivar.

Molecular cloning and characterization of GhERF105, a gene contributing to the regulation of gland formation in Upland cotton (Gossypium hirsutum L.)

Background: Upland cotton ( Gossypium hirsutum L.) is one of the most economically important crops worldwide . Cottonseed is a major significant source of fiber, feed, foodstuff, oil and biofuel products. However, the utilization of cottonseed is limited by the presence of small and darkly pigmented glands that contain large amounts of gossypol, which is toxic to human beings and other non-ruminant animals. To date,some progress has been made in the pigment gland formation, but the underlying molecular mechanism of pigment gland formation was still unclear. Results: In this study, we identified an AP2/ERF transcription factor named GhERF105 (Gh_A12G1784), which is involved in the regulation of gland pigmentation, from comparative transcriptome analysis of the leaf transcriptome from two pairs of glanded and glandless accessions, which are CCRI12 and CCRI12XW, L7 and L7XW. This gene encoded an ERF protein containing a converved AP2 domain localized in the nucleus with transcriptional activity., and it showed the high expression in glanded cotton accessions that contained much gossypol. Virus-induced gene silencing(VIGS) against GhERF105 caused the dramatic reduction in the number of glands and significantly lowered levels of gossypol in cotton leaves. GhERF105 showed the patterns of spatiotemporal and inducible expression in the glanded plants. Conclusions: These results suggest that GhERF105 contributes to the pigment gland formation and gossypol biosynthesis in partial organs of glanded plant. It also provides a potential molecular basis to generate ‘glandless-seed’ and ‘glanded-plant’ cotton cultivar.

Molecular cloning and characterization of GhERF105, a gene participated in the regulation of gland formation from cotton (Gossypium hirsutum L.)

Background Gossypium hirsutum L. (cotton) is one of the most economically important crops globally. Cottonseed is the significant source of fiber, feed, foodstuff, oil and biofuel products. However, the utilization of cottonseed was limited by the presence of small and darkly pigmented glands that contain large amounts of gossypol, which is toxic to human beings and other non-ruminant animals. To date, there has been some progress in the pigment gland formation, but the underlying molecular mechanism of pigment gland formation was still complicated and unclear. Results In this study, we identified an AP2/ERF transcription factor named GhERF105 (Gh_A12G1784), which was involved in the regulation of gland pigmentation, from comparative transcriptome analysis of the leaf of two pairs of glanded and glandless accessions, which are CCRI12 and CCRI12XW, L7 and L7XW. It encoded an ERF protein localized in the nucleus with transcriptional activation activity containing a conserved AP2 domain, and showed the high expression in glanded cotton accessions that contained much gossypol. Virus-induced gene silencing against GhERF105 caused the dramatic reduction in the number of glands and significantly lowered levels of gossypol in cotton leaves. GhERF105 showed the patterns of spatiotemporal and inducible expression in the glanded plants. Conclusions These results suggest that GhERF105 participates in the pigment gland formation and gossypol biosynthesis in partial tissue of glanded plant. It also provides a potential molecular basis to generate ‘glandless-seed’ and ‘glanded-plant’ cotton cultivar.

Identification of the genes and pathways associated with pigment gland morphogenesis in cotton by transcriptome profiling of near-isogenic lines

Cottonseed protein is underutilized due to the presence of pigment gland containing a toxic compound called gossypol. Cotton produces gossypol and related compounds in various tissues to protect itself against microbial, insect, and rodent attacks. Understanding the mechanism of cotton pigment gland formation and regulation of gossypol biosynthesis will greatly facilitate the research efforts in developing a cotton variety with a gossypol free seed and normally glanded foliage. In this study we make use of near-isogenic lines of cotton pigment gland to screen the genes related to gland morphogenesis applying both GeneChip and suppression subtractive hybridization (SSH) methods.We identified 880 differentially expressed genes associated with gland morphogenesis in cotton by comparing transcriptome profiles of cotton from glandless and glanded near-isogenic lines using a GeneChip. Gene ontology (GO) analysis showed that 880 genes were distributed mainly among the following GO categories: cellular process (14.45%), physiological process (14.23%), catalytic activity (9.21%), metabolism (8.99%), and cell parts (5.24%). Molecular pathway analysis revealed that these differentially expressed genes were involved in 58 KEGG pathways. Differentially expressed genes were also identified and isolated using suppression subtractive hybridization (SSH) with the same near-isogenic lines. A total of 147 ESTs were identified whose expression was either up- or down-regulated. Sequencing and BLAST analysis indicated that some of these genes were novel, while others were related to energy metabolism, transcription factors, and biotic responses. 13 genes were found to be differentially expressed both in SSH and GeneChip analysis. The expression pattern of these genes was verified by real-time PCR. The gene expression profiles produced in this study provide useful information on the molecular mechanism and regulation of gland formation and the related process in cotton. Of particular interest for future study are the genes identified by both SSH and GeneChip analysis. The outcomes are helping for our understanding of the development of specialised structures such as trichomes in plant species, from an applied and basic science perspective and promoting the application in molecular breeding.